Particles are clumping on each frame
To increase the accuracy and smoothness of simulations it can sometimes be helpful to scale the time up. 

Here a simple way of approximately stretching the time by 10. For every Particlesystem (3 in your example) multiply the End and the Lifetime of the emission by 10.



and divide the Timestep of the physics by 10.



In render settings multiply the End Frame and Frame Step by the same amount (10).



And render the frames as images. For videos you can reimport the frames in the VSE as image strip and render with the desired fps.